Is Mass Effect 1's final boss considered Synthetic or Organic?

I ask not in terms of classification semantics, but in regards to ammo.

• Tungsten Rounds inflict more damage to Synthetic enemies, while
• Shredder Rounds inflict more damage to organic enemies.

Does anyone know whether the boss' second form is considered Synthetic or Organic?

Solution 1:

The final boss is synthetic so you are going to want to use those Tungsten Rounds. That, along with things that allow you to bypass his shield initially will be very effective.

He is also pretty susceptible to biotics, especially singularity/lift.

Solution 2:

In the second form, the final boss is a synthetic.

So choose ammunition that is effective against synthetic enemies.